Ignition apparatus



Oct.'8, 1940. E. B. NowoslELsKl 2,217,232

IGNITION APPARATUS Filed Mayv 24, 1939 iNvENToR 'L7-H 3 BY z f www 39ATTORNEY Patented. ct. 8, 1940 IGNITION APPARATUS Edward B. Nowosielski,Sidney, N. Y., assignor to Bendix Aviation Corporation, South B end,Ind., a corporation of Delaware Application May 24,1939, Serial No.275,333

4 Claims.

This invention relates to internal combustion engines and moreparticularly to the ignition distribution system thereof.

The ignition systems in substantially all, if not 6 all, aircraftengines at the present time comprise a magneto which supplies lowtension current to the primary winding of an induction coil, thesecondary winding of which is connected to a movable distributorterminal.

E@ utor the high tension current from said secondary winding is directedin a predetermined sequence through a plurality of conductors connectedto the engine spark plugs. In systems of this character much diiiicultyhas been experienced, particularly in engines having a large number ofcylinders and at high altitudes, in preventing flash-overs in thedistributor unless the latter is made relatively large, heavy andcumbersome. Furthermore, it becomes necessary, in order to 9,0 avoidradio interference, to metallically shield the distributor and the longhigh tension conductors between the distributor and spark plugs, therebyincreasing the weight and introducing capacity and corona losses whichdecrease the intensity of the sparks and efficiency of the engine.Another difficulty which is inherent in systems of the above characterresides in the fact that a single circuit breaker is employed foreiecting the necessary interruptions in the primary circuit of theinduction coil. In modern high-speed multiplecylinder engines the largenumber and rapidity of these interruptions often over taxes the breakermechanism, as well as the induction coil.

It is accordingly one of the objects of the present invention to providea novel ignition distribution system wherein the foregoing difcultiesare overcome.

Ignition systems have been heretofore proposed wherein a separatecircuit including a cam o operated breaker and an induction coil isprovided for each individual plug. These prior systems have not,however, been suitable for high speed engines. It is accordingly anotherobject of the invention to provide a novel ignition distribution systemof the above character which is adapted for use on a high speed enginehaving a large number of cylinders, such as 14 and 18 cylinderdouble-row radial engines, for example.

Still another object is to provide a novel battery ignition system forinternal combustion engines for use in high speed engines wherein am-pletime is insured for adequatev building up of the current in the primarywinding of the induction coils.

A further object is to provide a novel radio From the distrib-y (Cl.12S- 148) shielded low tension distribution system for high speedengines.

The above and further objects and novel features of the invention willmore fully appear from the following detailed description when the same5 is read in connection with the accompanying drawing. It is to beexpressly understood, however, that the drawing is for the purpose ofillustration only and are not intended as a denition of the limits ofthe invention, reference 10 being primarily had for this latter purposeto the appended claims.

In the drawing wherein like reference characters refer to like partsthroughout the several views: f 15 Fig. 1 is a diagrammatic frontelevation partly in section and with parts broken away illustrating oneform of apparatus embodying the invention;

Fig. 2 is a side elevation, partly in section and with parts brokenaway, of the breaker mechazo nism shown in Fig. 1, the section beingtaken substantially along line 2-2 of Fig. 1;

Fig. 3 is a sectional view on an enlarged scale v of one form ofshielded induction coil which may be used in carrying out the invention;and, 25

Fig. 4 is a wiring diagram showing a portion of the distribution systemof Fig. 1.

A single embodiment of the present invention is illustrated in theaccompanying drawing, by way of example, in the form of a radio-shieldedig- 30 nition distribution system adapted for use on a nine cylinderhigh speed radial aircraft engine. In the form shown the source of lowtension electrical energy is constituted by a battery I0, one terminalof which is connected through an ig- 35 nition switch II and conductorI2 to the stationary contacts I3 of each of a plurality of circuitbreakers and the other terminal of which is connected to ground at I4;The current to each spark plug of the engine is controlled by oneoi osaid breakers, and an independent circuit, including an induction coilmounted on the engine cylinder near the spark plug, is provided betweeneach plug and the corresponding breaker points.

Referring more particularly to Figs. 1 and 2, the 45 form of breakermechanism illustrated comprises a pair of separable contacts I3, I5 foreach cylinder I6 of an engine which is only partially shown. Nine pairof breaker contacts, one pair for each cylinder, are shown circularlyarranged in a 50 single plane around a cam shaft Il which projects intoal two-part housing I8, I9 and is rotatably mounted to be driven by theengine crank shaft in any suitable manner well-known in the art. HousingI8, I9 may be secured to the engine cas- 55 ing by means of radiallyprojecting ears 28. Stationary contacts I3 are mounted ontsuitablebrackets 2| which are preferably adjustably carried by an annularinsulating plate 22 which is in turn xedly secured in housing member I8.Mounted on the opposite side of plate 22 and electrically connected tobrackets 2| is a conductor ring 23 which is connected at 24 to oneterminal of battery I8 by means of lead I2. Movable c'ontacts I5 arepreferably carried by sultable spring arms 25 which are mounted on andelectrically insulated from brackets 2l at 26. Arms 25 may serve ascurrent conducting means, as well as means for normally holding movablecontact points I5 in engagement with fixed contact points I3. Alsomounted in casing I8 are a plurality of small condensers 21, one of thelatter being connected across each pair of contacts I3,-

I5, as best seen in Fig. 4.

The fixed end of each contact arm 25 is connected by a suitableinsulated conductor 28 to the primary winding 29 of a small inductioncoil 38 which may be secured, `as'by means of brackets 3l, to enginecylinder I6 near a spark plug 33 extending into said cylinder. Thesecondary winding 32 of each of the coils 38 may be electricallyconnected to the central electrode of its associated spark plug 33 by arelatively short high tension conductor 34.

Preferably both the high and low tension portions of the above-describedcurrent distribution system are shielded to prevent interference Withradio reception by electrical and magnetic radiations from the liveconductors. For this purpose, shielded spark plugs of the generalcharacter shown in the copending application of Roy T.

Hurley, Serial No. 102,298, filed September 24,

1936, may be employed and the high tension secondary conductors 34 maybe enclosed in exible metallic conduits 35 detachably connected to thespark plugs at one end in any well-known manner and at the other end toa shielding cap 36 of known construction that is removably secured bymeans of a bale 31 to a metallic casing 38 surrounding each inductioncoil 30. Although it is not essential that the primary or low tensionconductors be radio shielded, the same may be provided with shieldingconduits 39 which are detachably connected by means of nuts 40 tonipples 4I threaded into spaced openings around the periphery of casingI8. It will thus be seen that the necessary shielding in thedistribution system of the present invention is materially less than indistribution systems now in common use.

Means are provided for controlling the opening and closing of the pairsof contact points I3, I5 in a novel manner to thereby insure asufficient build up of current in the primary winding 29 of eachinduction coil 30 before the circuit containing the same is broken inorder that a good spark at the spark plug will be assured. In the formshown said means includes a cam 42 on shaft I'l, the two lobes 43 and 44of which are adapted to engage followers 45 mounted on the free ends ofspring arms 25. The annular extent of lobes 43 and 44 is proportioned,in accordance with the spacing of the pairs of contacts I3, I5 so thatthe flow of electrical current to the primary wihdings of coils 3Il,which are to be successively energized, will overlap, so to speak, i.e., so that while a spark is occurring in one cylinder, current will beflowing from battery I8 to one or more of the coils 3Ilassociated withcylinders to be subsequently fired. Each pair of contacts is permittedto close for an appreciable interval prior to the opening thereof bycamA42, said interval being greater than the time between successivesparks in the various cylinders and sufficiently long to permit anadequate build-up of current in the induction coils to insure a goodspark at plug 33 when the primary circuit is broken.

This, in the illustrated embodiment (Fig. 1) contacts I3, I5 at a areabout to be opened, the contacts at b are being held in open position bythe lobes of cam 42, the contacts at c are about to be permittedto closeand the contacts at d are in closed position for conductinguni-directional currents from battery I0 to the respective inductioncoils associated therewith. Accordingly, when the spark plug in onecylinder is caused to fire by the opening of the contacts at a, forexample, current is building up in the primary windings of the coilsconnected to the closed breakers at d. The importance of this novel modeof operation will be more readily understood when it is realized thatsome modern aircraft engines rotate at speeds as high as severalthousand revolutions per minute and have as many as 14 or 18 cylinders.It will be apparent that in such engines the time interval betweensparks even in a given cylinder is quite short and that the intervalbetween sparks in the cylinders which are successively red is extremelyshort. Accordingly, unless a system of the character above-described isemployed in modern high speed engines having large numbers of cylindersthe spark intensity may be insufficient to properly ignite the highlycompressed combustible charges in the engine cylinders and thus causeinefiicient operation and perhaps complete failure.

If desired all of the low tension conductors may emerge from housing I8,I9 through a common opening and extend through a manifold shieldingconduit to a manifold shielding ring secured to y the engine andpartially encircling the propeller shaft in a manner well-known in theart. Coils 38 may be secured directly to the manifold ring in the samemanner in which said coils are secured to the shielding caps 46 (Fig. 3)or shielding conduits corresponding to leads 39 may be interposedbetween the coils and the manifold ring. The latter may be in two partswith a cover secured to the body portion by means of through bolts orthe like.

There is thus provided a novel ignition distribution system adapted foruse in both high and low speed multiple cylinder engines wherein thenecessity for a distributor and extensive radio shielding is obviatedand wherein large losses due to capacity and corona effects areaccordingly eliminated. The novel system provided by the presentinvention also eliminates the usual diniculties encountered in presentignition systems at high altitudes. The present invention alsocomprehends a novel mode of operation in a low tension ignitiondistribution system for internal combustion engines.

Although only one embodiment of the invention has been illustrated anddescribed in detail, it is to be expressly understood that the same isnot limited thereto. For example, it will be apparent that the pairs ofbreaker points I3, I5 may be arranged in line instead of circularly andoperated by a plurality of cams axially disposed along a cam shaft. Itwill also be apparent that the lobes of the breaker operating cam orcams might be caused to function to operatively hold normallyLdisengaged breaker contacts in engagement. Various other changes mayalso be made particularly in the design and arrangement of ziol partsillustrated as will now be apparent to those skilled in the art Withoutdeparting from the spirit and scope of the invention. For a definitionof the limits of the invention, reference is had primarily to theappended claims.

Whatis claimed is:

1. In an ignition system for high speed multiple cylinder internalcombustion engines, the combination of aV source of uni-directionalelectrical current, a spark plug in each cylinder of said engine, aplurality of normally closed circuit breakers, means connecting saidsource to each of said circuit breakers, circuit means connecting eachof said circuit breakers to a different one of said spark plugsincluding an induction coil mounted adjacent the spark plug, a lowtension conductor connecting the breaker to the primary winding of saidcoil and a high tension conductor connecting the secondary winding ofsaid coil to the spark plug, and rotatable cam means for opening saidcircuit breakers in a predetermined sequence, one or more of saidbreakers being 4in closed position to permit flow of current whenanother of said breakers is opened by said cam means.

2. In an ignition system for a multiple cylinder internal combustionengine, the combination of a source of uni-directional electricalcurrent, a spark plug in each cylinder of said engine, an induction coilfor each of said cylinders, one of said coils being mounted near each ofsaid spark plugs, means for electrically connecting the secondarywinding of each of said coils to the center electrode of the adjacentspark plug, a plurality of circuit breakers, means connecting each ofsaid circuit breakers in circuit with the primary Winding of a differentone of said coils, means electrically connecting said circuit breakersto a common terminal of said source, and cam means operated by theengine for actuating said circuit breakers to simultaneously connect aplurality of said coils in circuit with said source and to open saidcircuits one at a time in a predetermined sequence.

3. In an ignition system for a multiple cylinder internal combustionengine, the combination of a source oi uni-directional electricalcurrent, a spark plug in each cylinder of said engine, a plurality ofcircuit breakers each including a pair of points, means for normallyholding the points of each of said circuit breakers in yieldingengagement, separate circuit means connecting each of said spark plugsin circuit with a dierent one of said circuit breakers, each of saidcircuit means including an induction coil mounted near the spark plugconnected therewith, and cam means operated by said engine for openingsaid circuit breakers in a predetermined sequence and permitting thesame to close, the period during which each circuit breaker is in closedposition being greater for a given engine speed than the intervalbetween the opening of two successiVely operated circuit breakers.

4. In an ignition system for a multiple cylinder internal combustionengine, the combination of a source of electrical current, a radioshielded spark plug in each cylinder of said engine, a radio shieldedinduction coil mounted adjacent each of said spark plugs, a radioshielded conductor electrically connecting the secondary Winding of eachof said coils to the center electrode of the spark plug adjacentthereto, the shielding of said conductors being electrically connectedto the shielding onthe corresponding coils and spark plugs, a pluralityof circuit breakers, means electrically connecting the lprimary windingof each of said coils to a different one of said circuit breakers, meansconnecting said circuit breakers to a common source of electricalenergy, and means for opening and closing said circuit breakers in apredetermined sequence.

EDWARD B. NOWOSIEISKI.

